This invention relates to a method of navigating a robotic machine to follow an edge, and more particularly to centering and vectoring a welding robot along the joint between two parts.
Automatic seam welding machines typically assume workpieces and resultant joints whose dimensions and geometries are consistent. This consistency allows the path of a welding torch to be preprogrammed. In applications where this consistency is not valid sensors combined with data processing algorithms are necessary to have the positioning system center itself along the joint.
Visually guided tungsten inert gas (TIG) and metal inert gas (MIG) welding is described in copending application Ser. No. 401,471, filed July 26, 1982, now abandoned, and continuation application Ser. No. 619,432, filed June 11, 1984, now U.S. Pat. No. 4,488,032, A. W. Case, N. R. Kuchar, and D. C. Peroutky. The center of a gas tungsten arc welding torch is cleared and the lens of the integral optical system is over the tungsten electrode; the molten weld puddle and weld region are imaged on the face of a fiber optic cable and transmitted to a video camera and hence to a controller. Concurrently filed application Ser. No. 401,473, now U.S. Pat. No. 4,450,339, N. R. Corby, discloses a molybdenum sleeve on the electrode which blocks light from the intensely bright arc and improves the image. The major goal of visually guided welding is the production of high quality welds automatically, and to this end information is needed from the vicinity of the arc. To produce a quality weld, the positioning system must progress along the joint to be welded such that the puddle remains centered over the joint. In copending application Ser. No. 451,219, filed Dec. 20, 1982, now U.S. Pat. No. 4,496,719 N. R. Corby, the arc welding torch is provided with a programmable laser pattern projector, having a remote light source and beam deflector that traces a particular pattern on the face of a fiber optic bundle and, on the torch, an exit projector and relay assembly. The structured light pattern, for instance thin parallel light stripes, is imaged onto the work within the field of view of the built-in puddle view optical system. At least two light stripes focused on the joint ahead of the weld puddle provide, after processing the image, data on joint topology and navigational information to control movement of the welding torch. These applications are assigned to the assignee of this invention.